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| United States Patent |
5,183,503
|
|
Greenberg
|
February 2, 1993
|
Method of shaker molding and composition therefor
Abstract
An improved molding powder which comprises alkali metal alginate, calcium
salt, tetrasodium pyrophosphate and filler, the alginate being from
Laminaria hyperborea. The mixture sets to form a rubbery object.
| Inventors:
|
Greenberg; Allen A. (3531 N. 47th St., Hollywood, FL 33021)
|
| Appl. No.:
|
882009 |
| Filed:
|
May 13, 1992 |
| Current U.S. Class: |
106/38.51; 106/38.3; 106/38.35; 106/779; 264/333 |
| Intern'l Class: |
C08L 005/00 |
| Field of Search: |
106/38.3,38.35,38.51,779
264/333
|
References Cited
U.S. Patent Documents
| 2769717 | Nov., 1956 | Cresson | 106/38.
|
| 3268348 | Aug., 1966 | Morrell | 106/38.
|
| 3282710 | Nov., 1966 | Morrell | 106/38.
|
| 3371135 | Feb., 1968 | Goodwin | 264/71.
|
| 3958997 | May., 1976 | Greenberg | 106/38.
|
| 3989220 | Nov., 1976 | Greenberg | 220/4.
|
Primary Examiner: Group; Karl
Assistant Examiner: Green; Anthony J.
Attorney, Agent or Firm: Wegner, Cantor, Mueller & Player
Claims
I claim:
1. In a method of forming a molded object which comprises mixing together
approximately 5-10 parts by weight of water and one part by weight of a
molding powder mixture consisting essentially of from 7 to 15 percent by
weight alkali metal alginate, a calcium salt in amount equal to about 1.2
times by wt. the amount of alkali metal alginate, and 3/4 to 3 percent
tetrasodium pyrophosphate, the remainder being a filler selected from the
group consisting of diatomaceous earth, silica, magnesium carbonate, and
kaolin, allowing the mixture to set and gel in a mold, and drying the
resulting gelled object outside the mold to form a smaller rigid object,
the improvement which comprises employing the alginate from Laminaria
hyperborea.
2. A method of forming a molded object which comprises mixing together
approximately 6 parts of water and one part of a molding powder consisting
essentially of from 7 to 15 percent alkali metal alginate from Laminaria
hyperborea, an amount of calcium sulfate equal to about 1.2 times the
amount of alkali metal alginate, and 3/4 to 3 percent tetrasodium
pyrophosphate, the remainder being an inert filler, all parts and
percentages being by weight, allowing the mixture to set and gel in a mold
to form a rubbery object, and drying the rubbery object outside the mold
to form a smaller rigid molded object.
3. A method as in claim 2 wherein the alkali metal alginate is
approximately 10 percent of the molding powder.
4. A method as in claim 2 wherein the filler is diatomaceous earth.
5. A molding powder mixture consisting essentially of 7 to 15 percent
alkali metal alginate from Laminaria hyperborea, an amount of calcium
sulphate equal to 1.2 times the amount of alkali metal alginate, and 3/4
to 3 percent tetrasodium pyrophosphate, the remainder being an inert
filler, all percentages being by weight.
6. A molding powder mixture as in claim 5 wherein the percentage of alkali
metal alginate in the molding powder is approximately 10 percent.
Description
This invention relates to a molding composition and to a method of molding
a child's plaything.
This invention relates principally to a novel molding powder mixture to be
employed in a method of using a molding apparatus which includes a
shaker-mixer device in which ingredients to be molded are added then are
shaken and mixed before setting in the mold. A suitable molding apparatus
is described in my prior U.S. Pat. No. 3,989,220 to which reference is
made for a preferred embodiment of molding apparatus.
This invention is also directed to the method of forming the molded object
in which water and a molding powder mixture are shaken together in a
shaker-mixer mold device to cause intimate mixing of the water and the
molding powder mixture; where the mixed water and molding powder mixture
passes directly to a mold cavity wherein the object is molded. The method
as such and suitable apparatus are described in my prior U.S. Pat. Nos.
3,958,997 and 3,989,220 respectively both of which are hereby incorporated
by reference.
OBJECTIVES OF THE INVENTION
An object of this invention is to provide a molding method in which a
molded plaything object of a strong rubbery-like consistency is formed
directly in the mold cavity. Surprisingly and unexpectedly the freshly
made molded object, i.e. the object when removed from the mold immediately
after the recommended 5-10 minutes molding time is of sufficient strength
to be handled and even played with by the youngster. Parenthetically it is
noted that the freshly made molded objects made with the molding mixture
materials described in my afore-mentioned prior patents were jelly-like
and initially were very weak. At best they were barely self-supporting.
They could not be handled immediately nor could they be played with by the
youngster for at least 24 hours. The alginate (gelling) materials
heretofore used resulted in molded objects that initially were so soft and
weak as to require an internal (plastic) support while they dried and
gained strength.
Another object of this invention is to provide a molding composition which
generates a molded object therefrom that shrinks quickly, while coherently
maintaining its molded shape, until ultimately a stiff object of
substantially smaller size than the freshly molded object but of almost
exactly the same shape results. Objects molded from the composition of
this invention may be shrunk much faster than the similar objects
described in my prior U.S. Pat. No. 3,958,997. This is a major marketing
advantage, since the customer for this product are children and typically
youngsters have no patience.
A further object of this invention is to provide a molding method and
composition from which the freshly molded plaything object undergoes
syneresis or loss of water therefrom. Both bound and unbound water leave
the molded object as it dries.
A further object of this invention is to provide a molding method and
composition from which the freshly molded plaything object is so strong
and tough that it can be placed in a microwave oven, then shrunk at an
accelerated rate, by microwave heating to evaporate water. Thus, a further
object of this invention is to provide a molding method and composition in
which the molded object can be subjected to accelerated shrinking and
drying by heating same in a microwave oven, e.g. fifteen minutes of
microwave treatment or less.
A still further object of the invention is to provide a molding method and
composition in which the initial viscosity of the mixing powder-water
admixture from which the molded object will be formed is high enough to
prevent leakage past the sealing surfaces in the mold (thereby causing a
mess). At the same time the molding mixture does not become highly viscous
so quickly as to impede mixing efficiency nor hamper its ability to flow
into the mold within about 60-120 seconds after mixing.
BRIEF STATEMENT OF THE INVENTION
Briefly stated, the present invention contemplates employment of the alkali
metal alginate made from Laminaria hyperborea as the alginate gelling
agent in the molding powder mixture compositions.
Thus, the present invention may be described succinctly as being an
improvement in the molding method and composition described in prior U.S.
Pat. No. 3,958,997 in that the alkali metal alginate from Laminaria
hyperborea is substituted for the alkali metal alginate employed
heretofore.
RATIONALE OF THE PRESENT INVENTION
Insofar as the inventor hereof was aware during the genesis of the
inventions of U.S. Pat. Nos. 3,958,997 and 3,989,220, all alginates
available to him are nearly the same, and all would exhibit more or less
the same properties as the sodium and potassium alginates employed in
practice of those patented inventions. It turns out that the inventor
hereof then had available to him and was then familiar only with the
algins and (alkali metal) alginates from sea weeds native to the North
American continent, and in particular with the alginates recovered from
giant kelp, i.e. from Macrocystis pyrifera, which species of sea weed
grows in abundance in the water off the California coast, in large dense
kelp beds. Principally, the alkali metal alginates of commerce in the U.S.
are recovered from (California coast) giant kelp.
By and large, the alkali metal alginates from Macrocystis pyrifera and from
most other species of sea weed, e.g. Ascophylklum nodosum and Laminaria
digitata, that are harvested commercially for their algin content are
reasonably similar in physical properties. It is the alginates from
Laminaria hyperborea which are different. The alginates from L. hyperborea
generate molded objects which exhibit unexpectedly advantageous
properties. Instead of being jelly-like and almost non-self-supportable
the freshly molded object as removed from the mold is coherent,
self-supporting rubbery in texture. Advantageously, objects molded with
the L. hyperborea alginates lose water through syneresis.
The L. hyperborea is recovered from the waters off the coast of Scotland.
Algin is a polysaccharide formed from mannuronic acid residues and
guluronic acid residues linked into segments of three different polymer
configurations. One segment consists essentially of repeating D-mannuronic
acid residues; a second segment consists essentially of repeating
L-guluronic acid residues; and, the third segment consists of alternating
D-mannuronic acid and L-guluronic acid residues. In the algin polymer as a
whole the ratio of mannuronic to guluronic residues varies somewhat
species to species. Below reproduced to illustrate species similarities
and differences are two Tables from a "Kelco" brochure entitled "Alginate
Products for Scientific Water Control" (probably published 1987).
TABLE 2
__________________________________________________________________________
Mannuronic Acid (M) and Guluronic Acid (G) Composition of
Alginic Acid Obtained from Commercial Brown Algae
Mannuronic Acid
Guluronic Acid
Species Content (%)
Content (%)
M/G Ratio
M/G Ratio Range
__________________________________________________________________________
Macrocystis pyrifera
61 39 1.56 --
Ascophyllum nodosum
65 35 1.85
(1.1)
1.40-1.95
Laminaria digitata
59 41 1.45 1.40-1.60
Laminaria hyperborea
31 69 0.45 0.40-1.00
(stipes)
Ecklonia cava and
62 38 1.60 --
Eisenia bicyclis
__________________________________________________________________________
TABLE 3
______________________________________
Proportions of Polymannuronic Acid,
Polyguluronic Acid, and Alternating Segments
in Alginic Acid Isolated from Brown Algae
Poly-
mannuronic
Polyguluronic
Acid Acid Alternating
Segment Segment Segment
Source (%) (%) (%)
______________________________________
Macrocystis pyrifera
40.6 17.7 41.7
Ascophyllum nodosum
38.4 20.7 41.0
Laminaria hyperborea
12.7 60.5 26.8
______________________________________
Thus, it may be seen in the above tabulated data that the alginic acid
compositions vary relatively little, species to species of the sea weeds
save that from Laminaria hyperborea. The Laminaria hyperborea algin
contains about half of the mannuronic acid content, nearly double the
guluronic acid content of the other algins.
The high polgulronic acid content in the algin from Laminaria hyperborea
causes the alginate from Laminaria hyperborea to exhibit substantially
different properties, property differences which are surprisingly and
unexpectedly advantageous than the other alginates. For example, the
alginates from Laminaria hyperborea forms relatively rigid gels (of
calcium alginate) which tend to undergo syneresis (which is loss of bound
water). In contrast the alginates from Macrocystis pyrifera or from
Ascophyllum nodosum form elastic (calcium alginate) gels which deformed
and which have markedly reduced tendencies toward syneresis; water can be
removed only by drying the molded object.
The published studies on the make-up of alginates have hypothesized that
the polymer segments made up of polymannuronic acid residues extends in a
relatively flat or gentle wave ribbon configuration (wherein the glucan
ring and the ribbon axis are equatorial and near to co-planar), whereas
the segments made up of polgulronic acid residues is configured like a
buckled or crinkled ribbon (wherein the glucan rings are linked
di-axially). In the presence of calcium ions two of the crinkled ribbons
orient face to face so as to cage a calcium ion within each pair of the
opposing bends in the crinkled ribbons, somewhat like how the opposing
upper and lower faces of a molded egg carton contains an egg inside each
compartment formed by the open spaces between the opposing upper and lower
surfaces of the egg carton.
Whatever the stereochemical reasons may be, a composition containing the
alginate from Laminaria hyperborea molds into a plaything object that is
self-sustaining on removal from the mold. The freshly molded object is
strong and rubbery. (Comparable objects made with other alginates as, for
example, the alginate from giant kelp, are weak, jelly-like, and barely
self-sustaining.) The child can handle and play with the molded object
immediately out of the molding apparatus. In addition, the molded object
immediately begin to experience syneresis which over time causes the
object to shrink and harden substantially. Desirably, the freshly molded
object is sufficiently sturdy to be subjected to accelerated dewatering by
heating in a microwave oven.
A preferred embodiment shaker-mixer-mold assembly is described in U.S. Pat.
No. 3,989,220 to which reference is made for details. This assembly
includes a measuring cup, a pair of mold sections which can be held in
engagement with the edge of the measuring cup so that the mold cavity of
the mold sections is in communication with the interior of the measuring
cup, and a holder member inside which the mold sections are held in
assembled relation to the measuring cup while the materials inside of the
measuring cup and mold cavity are mixed and shaken.
To form a molded plaything, water and a molding powder mixture are placed
in the measuring cup member, then the mold sections and the holder member
are assembled over the measuring cup. After this, the water and molding
powder mixture are shaken together inside this assembly to generate a
uniform mixture. Finally, the assembly is inverted with the measuring cup
member on top so that the now uniform fluid mixture will flow into the
mold cavity wherein setting takes place and the plaything becomes molded.
The molding powder mixture of this invention will contain the sodium or
potassium salt of the algin from Laminaria hyperborea. As has been pointed
out this alginate is extremely high in guluronic acid residues (being some
60% alpha-L-gulopyranosyluronic acid residues in 1 C conformation). Also
present in the molding powder mixture is a contributor of calcium ion,
i.e. a calcium salt, which, for example, may be calcium sulphate or
calcium lactate to generate the calcium alginate gel. A sequestrant like
tspp, tsp, spp, etc. to control calcium solubility while the algin
hydrates. A source of magnesium ion may be included in the mixture to
facilitate gelatinization. A filler which, for example, may be
diatomaceous earth is made part of the molding powder mixture to add
rigidity to the resultant molded plaything. All that is needed is to add
water, then mix and allow to set for 5-10 minutes.
Then the molded plaything is removed from the mold, it is coherent,
self-sustaining rubbery, rather than jelly-like as had been the case
heretofore with the other alginates. The plaything immediately begins to
dry through evaporation and syneresis, and shrinks accordingly but, as the
molded plaything object shrinks, it retains its shape to form ultimately a
rigid dried object which is a miniature of the original molded plaything.
Indeed, the miniature retains the proportions of the original molding
almost perfectly.
To begin a molding operation, the water is added to the measuring cup (not
shown) to a level line which indicates the proper amount to add. Then to
the water is added a batch of predetermined weight or volume of the
molding powder mixture. The quantity is, of course, consistent with the
quantity of water in the cup. In a preferred embodiment, the molding
powder mixture consists of the following proportions:
______________________________________
11 percent sodium alginate from Laminaria hyperborea
(for example, MANGUEL, DVT or MANGUEL, DMB)
14 percent CaSO.sub.4.2H.sub.2 O
1 percent anhydrous tetrasodium pyrophosphate
5 percent MgCO.sub.3
69 percent diatomeous earth (filler)
______________________________________
Optional colorant and preservatives can also be added.
All percentages are by weight, and all constituents are ground so as to
form a powder mixture. The weight of a batch of molding powder should be
approximately 20% of the weight of the water.
When the batch of molding powder and water has been added to a measuring
cup of the sort, illustrated in U.S. Pat. No. 3,989,220, the mold halves
are assembled atop the measuring cup with the mold holder to lock the mold
halves and the measuring cup together with the batch of water and molding
powder contained inside the mold halves and measuring cup. The aqueous
mixture immediately becomes relatively viscous, and so does not leak from
the assembly. Then the assembly may be shaken for approximately 30 seconds
to thoroughly mix the molding powder and the water together. Thereafter,
the assembly should be upended, cup on top, so the viscous but still fluid
mixture flows into the mold cavity, and over time sets therein into a
rubbery gel to become the freshly molded plaything. After approximately 5
minutes, the assembly may be taken apart, disassembled (as described in
U.S. Pat. No. 3,989,220) and the rubbery molded plaything object removed.
As removed from the mold halves, the freshly molded plaything object
exhibits a coherent rubbery consistency. As the plaything loses water
through syneresis and evaporation, it shrinks proportionately so as to
retain its shape and appearance. Eventually, after a few days of drying at
room temperature, or 1 day of drying in an air stream (fan) or microwave
heated for 15 minutes, the plaything becomes a rigid dry to the touch
object having a volume of approximately one-third the original volume of
the freshly molded subject. In this regard there is little difference from
the molded object described in U.S. Pat. No. 3,958,997.
Desirably the improved firmness (i.e. rubbery rather than jelly-like) of
the freshly molded object plaything attributed to substitution of the
alginate from Laminaria hyperborea for the giant kelp alginate, allows the
youngster to accelerate drying by placing the freshly molded plaything
object in a microwave oven. Less than fifteen minutes (at full microwave
power) will dry a freshly molded plaything object thoroughly.
On the whole, the proportions of alkali metal alginate from Laminaria
hyperborea to be used may vary from about 7 to about 15 percent of the
molding powder mixture (dry basis) with the percentage of calcium salt,
e.g. CaSO.sub.4.2H.sub.2 O always being about 1.2 times the percentage of
alkali metal alginate, wt/wt basis. The percentage of the tetrasodium
pyrophosphate may be varied from 3/4 percent to approximately about 3
percent, but with more than 3 percent tetrasodium pyrophosphate, setting
or gelling time becomes more lengthy, may be one-half hour or more. Large
enough percentages of tetrasodium pyrophosphate to result in setting or
gelling times longer than one-half hour, might well be in excess of the
youngster's patience as well as a degradation of tensile strength.
The balance of the molding powder mixture to 100% wt/wt, is the filler.
Diatomaceous earth is the preferred filler for inclusion in the molding
powder mixture composition but other inert fillers may, of course, be used
in place of diatomaceous earth, e.g. silica, magnesium carbonate, and
kaolin (china clay).
As has already been pointed out preferred practice molding uses about 6
parts of water per part of molding powder mixture. More generally, 5-10
parts of water per part of molding powder mixture may be used.
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